It took them 17 years to update the EF 85mm f/1.2 L, so I am not expecting a mk II for the 50mm from 2006 anytime soon. Basically it already is an update for the f/1.0 L (shorter MFD, weather sealing, nearly half the weight, less than half the price).
The EF 50mm f/1.4 is getting dated too, I am considering replacing mine with either a Sigma f/1.4 or a Zeiss f/2.0 because I focus manually most of the time anyway.